File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

MSG file extension

Outlook Mail Message

Text Files

JAR file extension

Java Archive File

Executable Files

ASF file extension

Advanced Systems Format File

Video Files

PIF file extension

Program Information File

Executable Files

AVI file extension

Audio Video Interleave File

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files

MDF file extension

Media Disc Image File

Disk Image Files

GAM file extension

Saved Game File

Game Files

TARGZ file extension

Compressed Tarball File

Compressed Files

NES file extension

Nintendo (NES) ROM File

Game Files

RSS file extension

Rich Site Summary

Web Files

PDF file extension

Portable Document Format File

Layout Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

AIF file extension

Audio Interchange File Format

Audio Files

BMP file extension

Bitmap Image File

Raster Image Files